Our long term goal is to use Volvox carteri as a model for exploring the molecular mechanisms by which control genes exert their effects during eukaryotic development. Our research focuses on the regA locus, which suppresses reproductive development in somatic cells, and the sex c loci, which suppress sexual development in the absence of an exogenous sexual inducer. Our major objectives for the next granting period will be: 1) Complete a description of the patterns of in vivo synthesis of major polypeptides in wild type and mutant strains undergoing asexual and sexual development. 2) Relate these to patterns of functional messenger RNA accumulation, by use of cell-free translation systems. 3) Isolate, from a genomic bank of Volvox DNA sequences that has already been developed, sequences that are expressed in a regulated manner in the developmental pathways we are studying. 4) use these as probes to explore the patterns of transcriptional regulation exerted by the control genes of interest. In addition, we intend to capitalize on our observation that just before the time regA gene is believed to function it becomes selectively sensitive to mutagenesis; we believe that this may provide the means for identifying both the gene and its product and determining both how it is activated in somatic cells, and how it executes its important control functions. The health-relatedness of this research derives from the analogy between somatic cell regeneration in regA mutants of Volvox and neoplasia in higher forms. In regA mutants the somatic cells (which are stably differentiated and postmitotic in wild type) transdifferentiate and reproduce without restraint. Understanding regA function could provide novel insights into approaches for exploring growth control and neoplastic transformation in higher eukaryotes.